An electronic component, such as a graphics processing unit or a memory device, may be used in variety of electronic systems, such as various models of a cell phone or a tablet computing device. For the electronic component to be used in a particular electronic system, the electronic component detects that it is in an environment of the particular electronic system and is configured for use with the particular electronic system. For example, if a graphics processing unit is to be used in a large-screen model of a cell phone, is must be configured for use in the large-screen model environment, rather than a small-screen model environment.
Conventional techniques use two-state input pins for detecting that an electronic component is in an environment (also called an “electronic-component state”), such as general purpose input/output (“GPIO”) pins. The electronic-component state is used to determine a corresponding configuration of the electronic component for use with the electronic system. The state of the electronic component may be determined based at least in part on states of one or more GPIO pins. To determine a state of a GPIO pin, the electronic component detects whether the GPIO pin is coupled to a high voltage (e.g., a voltage that would be read by a logic gate as a 1) or a low voltage (e.g., a voltage that would be read by a logic gate as a 0). In this way, the GPIO pin is a two-state input, having one state as a high voltage state and another state as a low voltage state.
The electronic system may provide the high voltage or the low voltage using an external pull resistor coupled to the GPIO pin. A pull resistor is used to pull a voltage of a signal toward a reference voltage to which it is coupled, thereby improving accuracy in determining the state of the GPIO pin. A pull resistor that is coupled to a low voltage is called a pull-down resistor. A pull resistor that is coupled to a high voltage is called a pull-up resistor.
If the electronic component includes more than two candidate configurations, multiple GPIO pins must be used to detect a combined pin state. For example, two conventional two-state GPIO pins may be used to provide four candidate electronic-component states based on combined pin states (0,0), (0,1), (1,1), and (1,0). Thus, an electronic component configurable with more than two electronic component configurations must reserve at least two GPIO pins for determining an electronic-component state. An electronic component configurable with more than four electronic component configurations must reserve at least three GPIO pins for determining an electronic-component state. As electronic components are designed for increased versatility, the electronic components will require more and more GPIO pins for configuration information. However, as more GPIO pins are used for configuration, the chip must be large to accommodate the GPIO pins.
This background provides context for the disclosure. Unless otherwise indicated, material described in this section is not prior art to the claims in this disclosure and is not admitted to be prior art by inclusion in this section.